Thaumatin-like protein(Pe-TLP)acts as a positive factor in transgenic poplars enhanced resistance to spots disease

Thaumantin-like proteins (TLPs), a class of pathogenesis-related (PR) proteins, have the potential to enhance plant resistance against fungal pathogens. They are thought to have different functions in other physiological processes. In this study, a TLP gene (PeTLP) was cloned from poplar cultivar (Populus deltoides x P. euramericana 'Nanlin895'). According to bioinformatic analysis results about Pe-TLP (protein encoded by PeTLP gene), although typical thaumatin domain exists in its protein structure, Pe-TLP shares a close relationship with osmotin-like protein family according to KEGG metabolic pathway data. ATP assay showed that Pe-TLP had biological activity, but no direct fungicidal activity according to the result of assay of antifungal activity. Motif and structure differences may result in the poplar TLP protein not being able to effectively act on pathogens. And we grew transgenic Nanlin895 poplars over-expressed the PeTLP gene. Higher expression levels of TLP protein in transgenic poplar plants were observed using SDS-PAGE analysis. Although the Pe-TLP itself had no effect on pathogenic strain, transgenic plants with higher expression levels of PeTLP showed enhanced resistance against spots disease, and total proteins extracted from leaves of PeTLP over-expression lines showed obvious inhibitory effect on the growth of fungi under in vitro conditions. Our results suggest that the protein encoded by PeTLP functions as an elicitor of other anti-fungal proteins. Also, our findings provide a strong basis for developing a commercial poplar with the characteristics of spots disease resistance.